title: Development of a highly sensitive bacteria detection assay using fluorescent pH-responsive polymeric micelles.
abstract: The detection and control of bacteria is extremely important in the safety of food products and health systems. The conventional microbiological methods based on culture enrichment techniques and plating procedures are highly sensitive and selective for bacterial detection but are expensive, cumbersome and time-consuming. Here we report the development of a simple and sensitive bioassay to detect Escherichia coli (E. coli) bacteria by using self assembled pH-responsive polymeric micelles that have been bioconjugated to anti-E. coli (capturing agent). Poly(ethylene glycol-b-trimethylsilyl methacrylate), containing silicon moieties that can be cleaved under mildly acidic conditions, was synthesized and self-assembled into micelles, that were loaded with a fluorescent dye (1-methylpyrene). The polymer silicon protecting groups are used as a tool to remotely activate the dye release by means of pH. The high sensitivity of the newly developed bioassay, which is capable of detecting 15 bacteria per milliliter of solution, is due to an amplification effect generated by the optical signal of millions of fluorophores released from a single micelle upon attachment to a bacterium. Fluorescence probing involves the measurements of changes in the emission spectra, through the disappearance of the excimer band, which only occurs when the dye molecules are trapped within the polymeric micelles.
authors.affiliation: King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, P.O. Box 2454, Saudi Arabia. fmouffouk@ksu.edu.sa.pt
authors.forename: Fouzi
authors.initials: F
authors.lastname: Mouffouk
authors.forename: Ana M Rosa
authors.initials: AM
authors.lastname: da Costa
authors.forename: Jorge
authors.initials: J
authors.lastname: Martins
authors.forename: Mohammed
authors.initials: M
authors.lastname: Zourob
authors.forename: Khalid Mustafa
authors.initials: KM
authors.lastname: Abu-Salah
authors.forename: Salman A
authors.initials: SA
authors.lastname: Alrokayan
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification*; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D011108:Polymers / Q000737:chemistry*
chemical_list: D008823:Micelles; D011108:Polymers